/**
 * Copyright (c) 2010, Todd Ginsberg
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 *    * Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *    * Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *    * Neither the name of Todd Ginsberg, or Gowalla nor the
 *      names of any contributors may be used to endorse or promote products
 *      derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 *  Also, please use this for Good and not Evil.  
 */
package com.ginsberg.gowalla.rate;

/**
 * RateLimiter objects enforce an arbitrary set of rules for determining
 * the rate at which requests may be made. 
 * 
 * @author Todd Ginsberg
 */
public interface RateLimiter {
	
	/**
	 * This is called immediately before a request is made to the
	 * remote Gowalla API.  This method may do anything it wants to
	 * determine if a request should proceed.  If false is returned
	 * from this method, the request is not made and a RateLimitExceeded
	 * exception will be thrown back to the caller.  Otherwise, the
	 * requst will be allowed to continue.  
	 * 
	 * If an implementation wanted to limit the number of concurrent
	 * requests to Gowalla, this would be a good place to do it.
	 * 
	 * @return true if the request may proceed, false otherwise.
	 */
	public boolean preRequest();
	
	/**
	 * This is called immediately after a request, successful or not, in 
	 * order to release any locks or resources acquired by the preRequest()
	 * method.  
	 */
	public void postRequest();

}
